(1) Field of the Invention
The present invention relates to a time division multiple accessing satellite communication system.
(2) Description of the Prior Art
As well known in the prior art, the time division multiple accessing satellite communication system has a common communication channel interconnecting a central station and a plurality of remote stations through a satellite transponder. The common communication channel is divided into frames each having a plurality of time slots of a length. The central station transmits a broadcasting signal to the satellite transponder as a transmitted signal. The broadcasting signal has control information including a timing signal for controlling the remote stations. Each of the remote stations receives the transmitted broadcasting signal through the satellite transponder as a received broadcasting signal and derives the control information and the timing signal from the received broadcasting signal. The remote station generates a slot timing based on the derived timing signal and transmits a packet signal to one of the time slots according to the control information at the slot timing generated. A reference is made to, for example, U.S. Pat. No. 4,736,271 by Tejima et al, assigned to NEC Corporation.
The broadcasting signal from the central station is important in the multiple accessing satellite communication system. If the remote stations cannot receive the broadcasting signal due to rain or local power fault in the area where the central station is located or due to fault of a transmitter in the central station, the remote station cannot obtain the control information so that the communication cannot be effected in the system.